After consensus in the aftermath of 11 September, American politics looks to be returning to a more usual pattern - of sorts.

In recent weeks Democrats and Republicans in Congress have revived their differences on issues ranging from airport security to how best to stimulate the flagging economy.

The administration has not disguised its determination to aggressively pursue those it believes may be involved in terrorism.

But the most significant and controversial debate has been over an issue that would have seemed extraordinary before 11 September.

Many members of Congress are now locking horns with the White House over civil liberties and how best to protect them. The US now has the capacity to try suspects in military tribunals, and enables its government to monitor conversations between a detainee and his lawyer.

Tackling the enemy within is quickly becoming the most sensitive internal debate of America's new war.

Determination

The administration has not disguised its determination to pursue those it believes may be involved in terrorism.

On 8 November, Attorney General John Ashcroft said the Justice Department was modelling its tactics on the 1960s Justice Department of Robert Kennedy which, Mr Ashcroft said would "arrest a mobster for spitting on the sidewalk if it would help in the fight against organised crime".

Congress has already passed an anti-terrorism bill, signed into law by President Bush on 26 October. The bill expanded the definition of terrorism, and increased the search and surveillance powers of investigators.

Beefed up security means longer airport queues

However, since the bill was signed, a number of additional measures have also been announced, most without any Congressional consultation.

On 13 November, the administration seized some of the judiciary's power when President Bush signed an executive order allowing alleged terrorists to be tried in military tribunals.

The order means that such courts would be able to impose sentences as severe as the death penalty on a two-thirds vote, hold trials in secret and rely on evidence that may be rejected in a civil court.

Furthermore, suspects would have no right to a judicial review.

'Vital' measures

The US Government insists such measures are vital to protect US values and interests.

The White House compared the measures to the courts established by President Franklin D Roosevelt during World War II to try eight Nazi saboteurs who landed by U-boat on US soil in 1942.

The US quickly drew up a list of suspects for the attacks in New York

Unlike today however, Mr Roosevelt was backed by the Supreme Court and a Congress that had officially declared war.

The attorney general's decision to allow the government to listen to conversations between people in custody and their lawyers has provoked particular criticism.

The monitoring can last up to a year if the attorney general judges that there is "reasonable suspicion" that the suspect is conspiring to "facilitate acts of terrorism", and can be applied both to those already in prison and suspects who have been detained but not charged.

Questioning the legality of the move, the President of the American Bar Association Robert Hirshon said in a statement issued on 9 November that "these new rules run squarely afoul of the fourth and sixth amendments to the US Constitution.

The sixth amendment guarantees a right to counsel, but the new rules clearly violate that privilege, and therefore seriously impinge on the right to counsel."

The US Government is seeking more surveillance powers to combat terrorism

Concern has also been voiced over the prospect of racial profiling - suspects being rounded up on the basis of their ethnic background rather than specific criminal evidence.

John Ashcroft has indicated that he wants to see up to 5,000 men aged between 18 and 35 who entered the United States on non-immigrant visas since 1 January 2000 interviewed by police.

Police concern

According to a recent report in the New York Times, many US police chiefs are worried what a new era of federally sponsored racial profiling will do to race relations in communities across America.

The attorney general owes the country [and] certainly owes the Congress an explanation

Senate Judiciary Chairman Patrick Leahy

The American Civil Liberties Union has released a "Know Your Rights" pamphlet in seven languages, including Arabic, to advise non-US citizens who might be questioned by the authorities.

But what is angering politicians and civil liberties groups most is the curtain of secrecy that has been drawn in front of proceedings.

On 8 November the Justice Department announced it would no longer reveal how many people were being detained in custody.

Increasingly frustrated senators from both parties have been calling for John Ashcroft to give evidence to the Judiciary Committee.

Senate critical

The Chairman of the Senate Judiciary Committee, Patrick Leahy, has been particularly critical of John Ashcroft.

He told NBC's "Meet the Press" on 25 November that "the attorney general owes the country ... certainly owes the Congress ... an explanation."

Senator Leahy also warned that by ignoring some historic tenants of the American criminal justice system, the US risked looking "like some of the things we are fighting against".

The attorney general has so far declined to appear before the Senate, although it is now believed that he will appear before the committee in early December.

These are exceptional times that many argue require exceptional measures. But others are wary of the possible long-term costs to the concepts of freedom and liberty.